Various automotive lifts are currently known. Above-ground lifts typically employ a pair of opposing posts or columns positioned along respective sides of the vehicle and facing one another at right angles to the longitudinal axis of the lift bay. In a symmetric lift, a pair of symmetrically folding support arms are mounted to each column. The arms are mounted to be raised and lowered on their respective columns. The support arms also pivot together and apart in a scissor-like manner. A vehicle is driven between the columns and the arms are properly positioned beneath the undercarriage of the vehicle. Ideally, the lift arms are placed so that they respectively engage the undercarriage of the vehicle at equal distances forwardly and rearwardly of the center mass of the vehicle. The lift is then operated so that the arms raise and lower the vehicle between the columns.
Symmetric lifts provide generally satisfactory balance for most passenger cars. In addition, this type of lift allows the vehicle to enter the lift bay from either direction. However, symmetric lifts also exhibit a number of problems. After an automobile is properly positioned on the lift, it can be difficult, if not impossible, to fully open the vehicle's doors because they are obstructed by the lift columns. This frustrates the lift operator attempting to enter or leave the vehicle. The car doors are also apt to bump into the columns, which can damage the doors. Furthermore, it can be annoying, inconvenient and time consuming to properly adjust the position of an automobile having a short wheel base on the symmetric lift. This often requires that the car be moved repeatedly back and forth small distances so that the lift arms dear the vehicle's wheels but at the same time proper balance is obtained.
Asymmetric lifts have been developed as an alternative to the symmetric mechanisms described above. In this type of lift, each vertical column movably supports a pair of pivot arms that fold or collapse in the same direction. This contrasts with the symmetric lift wherein the pivot arms collapsibly fold in opposing directions. In most asymmetric lifts, the vertical support columns are positioned beside respective sides of the vehicle forwardly of the longitudinal midpoint or center of the mass of the vehicle.
The off-center positioning of the columns in an asymmetric lift allows much improved access to, and far easier opening and closing of the car's doors. The posts or columns are usually located sufficiently forwardly along the car so that the doors easily clear the columns when they are opened and closed. This allows the lift operator to conveniently enter and leave the vehicle after it is positioned on the lift. It is also quicker and easier to position automobiles having short wheel bases on an asymmetric lift.
Unfortunately, asymmetric lifts also exhibit a number of disadvantages. Because the lift arms do not extend to engage the undercarriage of the vehicle in a symmetric manner, it can be difficult and time consuming to property position and balance the vehicle on the lift. Proper balancing is critically important because a vehicle incorrectly balanced on the lift can present a serious risk of personal injury and property damage. Moreover, the driver's door on many vans is situated such that it strikes the support column of the asymmetric lift when the door is opened. Therefore, the asymmetric lift exhibits the same disadvantage for vans as the symmetric lift exhibits when used for a passenger car. Asymmetric lifts also lack the flexibility of symmetric mechanisms and are generally approachable by the vehicle in only one direction.
Many conventional asymmetric lifts are positioned such that they directly face one another on opposite sides of the vehicle bay. The arms supporting the vehicle thereby exert an uneven load on the carriage bearings of the lift. This tends to cause premature bearing wear, which can necessitate expensive repairs to the lift. At least one known lift has turned or rotated the columns so that they do not directly face one another. This has helped to alleviate uneven bearing wear somewhat. However, as with other asymmetric lifts, the columns in this mechanism are arranged along a transverse line that is substantially perpendicular to the longitudinal axis of the vehicle bay. As a result, most of the other problems associated with asymmetric lifts remain. In particular, it is difficult to open and close the doors of a van or similar vehicle because of interference from the columns. Safe and proper balancing also remains problematic.
Virtually all conventional above-ground lifts currently in use experience serious spacing problems. The work bays in most automotive garages have widths of approximately 10′-12′. The width of most conventional motor vehicle lifts is about 11′6″. As a result, fitting adjacent lifts within the space available in the garage can be complicated, if not impossible. Even in facilities where each bay has a width of 12′, this leaves a space of only about 6″ between the side-by-side columns of adjacent lifts. There is little, if any, room for the lift operators and other garage personnel to pass between the columns of the adjacent bays. With even narrower bays (e.g. those on the order of 10′ in width), this difficulty is exacerbated. It is virtually impossible to install most above-ground vehicle lifts in adjacent bays having such narrow widths. As a result, a garage having only a limited amount of space is severely restricted in the number of lifts that it can utilize. Some lifts have installed columns having an outside width of only about 10′ 8″, which increases the clearance between adjacent lifts. However, in such cases it becomes extremely difficult to open and close the doors of the vehicle due to the narrow spacing between columns. Lifts having such a narrow column spacing also restrict wide vehicles from being positioned on the lift.